#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <math.h>

int main()
{
	int  i = 0;
	double sum = 0;
	for (i = 1; i <= 100; i++)
	{
		sum = sum + (pow(-1 , i+1)) * 1 / i;
	}
	printf("%f\n", sum);
	return 0;
}